STAT3 and oral cavity squamous cell carcinoma: In addition, oral squamous cell carcinoma (OSCC) stem cell-derived EVs contain miR-21-5p, which activates the phosphoinositide 3-kinase (PI3K)-mTOR-signal transducer and activator of transcription 3 (STAT3) signaling pathway in OSCC cells, leading to cisplatin resistance in non-OSCC stem cells.